1. Field of the Invention
The present invention relates generally to magnetic heads for hard disk drives, and more particularly to magnetic heads having multiple layer write head induction coils, and methods for the fabrication thereof utilizing aspect ratio dependent etching such as the reactive ion etch (RIE) lag phenomena.
2. Description of the Invention
Magnetic heads commonly include write heads having two magnetic pole members and a flat, spiral induction coil disposed therebetween. Write head electrical current that passes through the induction coil creates a magnetic flux in the two magnetic pole members, and the magnetic flux passes through a write head pole tip, to write magnetic data bits onto the media, such as a hard disk, that is disposed proximate the pole tip. To improve the performance characteristics of write heads, efforts have been directed to increasing the magnetic flux that is generated by the induction coil in order to increase the magnetic field at the pole tip, such that data bits can more easily and reliably be written onto the magnetic media.
One prior art method for increasing the write head magnetic flux is to increase the number of induction coil turns that are fabricated between the two magnetic pole pieces. These efforts have lead to redevelopment of multiple layered induction coils. However, such multiple layer induction coils, as are known in the prior art, are generally difficult to reliably fabricate. Specifically, the prior art dual coil fabrication methods have generally employed well known photo-lithographic techniques which have resulted in problems related to the difficulty of removing the plating seed layer between coil turns, as well as a difficulty in filling the space between coil turns with alumina, or a similarly acceptable insulation material, following the plating of the coil turns. The present invention utilizes a selective plasma etching fabrication technique that takes advantage the aspect ratio dependent etching properties of the well knownRIE lag phenomena, wherein etched structures having differing widths are etched to differing depths, to avoid the prior art problems.
The magnetic head of the present invention includes an induction coil and electrical interconnects that are fabricated in one step using an aspect ratio dependent etching process known as the RIE lag phenomena. A specific embodiment includes a dual layer induction coil having coil turns that are more accurately and reliably spaced due to the use of reactive ion etching fabrication techniques. Following the fabrication of the first magnetic pole (P1) an etch stop layer is deposited. Thereafter, a layer of an etchable insulation material is deposited, followed by the fabrication of an induction coil etching mask thereon. Utilizing a reactive ion etch process, induction coil trenches are thereafter etched into the etchable insulation material down to the etch stop layer. The first induction coil is then fabricated into the induction coil trenches, preferably utilizing standard electrodeposition techniques. Following a chemical mechanical polishing (CMP) step to remove excess induction coil material and the first induction coil etching mask, a second induction coil structure is fabricated upon the first induction coil. Initially, a second layer of etchable insulation material is deposited upon the first induction coil structure, followed by the fabrication of a patterned second induction coil etching mask upon the second etchable insulation material layer. A second reactive ion etch process is then conducted to etch the second induction coil trenches and electrical interconnect trenches into the second etchable insulation material layer. Significantly, the pattern openings for the induction coil trenches are narrower than the openings for the electrical interconnect trenches. The RIE etching process is conducted such that the interconnect trenches are etched down to the first induction coil interconnects, whereas the second induction coil trenches are not etched all the way through the second etchable insulation material layer. The second induction coil and interconnects are next fabricated into the second induction coil trenches and interconnect trenches, preferably utilizing electrodeposition techniques. Thereafter, excess induction coil material and the second induction coil etching mask are removed in a second CMP step. Thereafter, an insulation layer is deposited upon the second induction coil, followed by the fabrication of a second magnetic pole (P2) upon the insulation layer. In the preferred embodiments, the first and second etchable insulation material layers are composed of the same material.
It is an advantage of the magnetic head of the present invention that it includes multiple layered induction coils that are more reliably fabricated.
It is another advantage of the magnetic head of the present invention that it includes multiple layered induction coils having reduced spacing between coil traces due to the use of reactive ion etching techniques.
It is a further advantage of the magnetic head of the present invention that insulation between induction coil traces of multiple layered induction coils is more reliably fabricated.
It is an advantage of the disk drive of the present invention that it includes a magnetic head having multiple layered induction coils that are more reliably fabricated.
It is another advantage of the disk drive of the present invention that it includes a magnetic head that includes multiple layered induction coils having reduced spacing between coil traces due to the use of reactive ion etching techniques.
It is a further advantage of the disk drive of the present invention that it includes a magnetic head having insulation between induction coil traces of multiple layered induction coils that is more reliably fabricated.
It is an advantage of the method for fabricating a magnetic head of the present invention that a multiple layer induction coil is more easily and reliably produced.
It is another advantage of the method for fabricating a magnetic head of the present invention that the spacing between induction coil traces can be reduced by using reactive ion etching techniques.
The foregoing and other objects, features, and advantages of the present invention will be apparent from the following detailed description of the preferred embodiment which makes reference to the several figures of the drawing.